It has long been recognized that houses, utility buildings and other structures should be erected upon a foundation rather than simply being placed directly on the earth. In times past such foundations were often erected using cut or rough stone, rubble and the like. For a number of reasons, this type of construction has been largely replaced over the years by foundations made of poured concrete footings with a wall of hollow concrete blocks set in place thereon, and this kind of foundation is now standard in the building industry.
Typically, such foundations are constructed by first laying out the perimeter of the foundation wall with batter boards, grade stakes, nails and string. Then a crawl space area is excavated, and continuous footing trenches are dug, leveled and tamped. Reinforcing rods or elements are then placed in the trenches, and concrete is poured and allowed to set to form a footing for receiving the hollow concrete blocks.
The concrete blocks are then set by hand upon the poured footings, one at a time, using cement mortar as the leveling and bonding medium. Finally, the building is installed on the wall of concrete blocks and is secured thereto by any one of several methods. This process for foundation construction is obviously labor intensive and calls for a number of different skills by the workmen. It is also subject to a number of construction errors, such as can occur when foreign materials like pieces of wood are utilized to initially support the reinforcing elements, and are then not removed before pouring the concrete.
There are in fact a number of disadvantages with this kind of foundation construction, including the following:
1. Structural quality of the poured continuous footing is difficult to control on the job site because of failure to properly install reinforcement elements, earthen footing trench walls caving in before or during the placement of the concrete, and weather conditions such as heavy rains occurring before the concrete has been poured and sets. These conditions usually result in later differential settlement of the footings at points where their structural integrity is impaired, which can cause resultant damage to the concrete block wall and to the building structure resting on the footings. In the case of the block walls, the resulting damage can be in the form of continuous cracks in the mortar joints, or even ultimate block failure if the weight of the building is shifted and becomes improperly applied. The building itself can be damaged to a lesser or greater extent, ranging from wall cracks and nonaligned doors and windows, to collapse of the whole building.
2. The hollow concrete blocks normally used are porous and, unless properly sealed and painted, they will continually entrap moisture which can then cause structural damage, especially during periods of alternate freezing and thawing. The block walls also normally provide a damp crawl space area and offer no effective insulation against the passage of heat.
3. Because of the complexity of the construction, poured in place footing and hollow concrete block foundations require careful coordination between a number of different workmen skills, which skills may or may not always be available and, the practice of which, in all cases requires many hours of increasingly expensive labor.
4. The construction of poured in place footing and hollow concrete block foundations is especially dependent upon relatively lengthy periods of good weather, because of the time required for construction and the use of earthen trenches for the footings.
5. The hollow concrete block walls placed on the footings are not an especially aesthetically pleasing form of construction, and present an unfinished look unless further labor intensive and expensive steps are taken to dress them up.
All of these disadvantages are heightened when working with the modular or prefabricated buildings of today, which arrive at the job site ready to be installed in functioning condition. The transport of these manufactured buildings is expensive and must be properly scheduled to achieve economically satisfactory results, but this scheduling is difficult to achieve in many instances because of the unanticipated delays often involved with the normal poured footing and concrete block type of foundations.
The need for better foundation construction methods has been recognized, and there have been attempts at providing improved foundations. One such effort is represented by U.S. Pat. No. 4,107,889, wherein precast concrete beams are installed upon poured-in-place piers utilizing hollow pedestals, reinforcement elements, and poured concrete for the actual installation. However, again the basic problems with pouring concrete into earthen forms is present, and the workmen skills required for construction are still extensive and the process lengthy.
There is thus need for an improved method and system for foundation construction designed to reduce to a minimum the type and amount of skilled labor needed at the job site, and which will produce significantly superior foundations of uniformly high quality at a lower cost than is possible today. The present invention is intended to satisfy that need.
There is also a greater need today than ever before to include energy conservation measures in building construction, a matter which has been essentially totally ignored over the years in foundation construction, in part because the conventional poured footing and concrete block foundation does not lend itself to energy conservation measures. The present invention is also intended to address the need for energy conservation in foundations, and at the same time provides unique opportunities for taking advantage of the sun as an energy source.